Conventional tactile sensors can only detect simple physical values such as pressure, but can hardly measure multi-directional movements in touch with the surface of objects.
We propose a soft tactile sensor using an Ionic Polymer-Metal Composite (IPMC or known as ICPF). IPMC is excellent in softness, durability, easy molding, and so on. Many applications have been developed using as IPMC actuators. IPMC can also utilized as a sensor, because a voltage on the both ends of the film changes by adding mechanical stimuli and bending the film. It is found experimentally that IPMC has the characteristics as a speed sensor because the output voltages were in proportion to the velocities of the end of films by making vibrational motions.
A tactile speed sensor that can measure the velocity vectors in 3-dimenstional movements was developed. The sensor has centroclinal structure made of silicone gel capsule, and four IPMC sensor modules were combined with the capsule inside in cross shape. The silicon gel capsule also seal in water, which is necessary for IPMC devices. The output voltages of each sensor were calibrated into the same maximum outputs because IPMC sensors have response variation. The amount of the velocity was estimated by calculating four outputs of each sensor modules. The direction of the movement can also be estimated by them only when the amount of the velocity exceeds the sufficient level. Experimental results show the sensor could estimate the velocity vector in real-time.